CC Madhya 22.81
This is a quotation from Śrīmad-Bhāgavatam (3.25.21). When the sages, headed by Śaunaka, inquired about Kapiladeva, the incarnation of Godhead, Sūta Gosvāmī, who was the topmost devotee of the Lord, quoted talks about self-realization between Vidura and Maitreya, a friend of Vyāsadeva’s. During these talks the topic of Lord Kapila had come up, and at that time Maitreya had repeated Kapiladeva’s discussions with His mother, wherein the Lord states that attachment to material things is the cause of conditioned life. When a person becomes attached to transcendental things, he is on the path of liberation.